Ronnie O'Sullivan was "glad" his bid for an eighth Masters title was over after struggling with illness in his 6-1 quarterfinal loss to Mark Allen.

O'Sullivan won the first frame with a break of 75, despite calling a foul on himself as he cued over a red to attempt a difficult black.

But that was as good as it got for the five-time world champion at Alexandra Palace as Allen responded to take six straight frames and advance to the semifinals.

"I'm glad it is over. It was a bit of a tough match for me," O'Sullivan told the BBC. "I don't make excuses. I had to show up. If I was a footballer I would probably have missed this game and they'd have put somebody else in for me.

"But in an individual sport you sometimes have to just get out there and do it. If I had pulled out there would have been murders, everyone would've been shouting and screaming. I just thought, 'just turn up, give it a go'. I wasn't able to turn it around."

O'Sullivan insisted his illness was no worse than in his earlier win over Marco Fu and was magnanimous in defeat.

"I'm struggling. I don't know what it is, whether it's a virus," O'Sullivan added. "I've had it before and it's very difficult when you're getting dizzy spells. I gave it a go and wasn't good enough. You have to give people credit. It was a fantastic performance, fantastic game."